Inflatable manometers

ABSTRACT

An inflatable air cell pressure transducer. The air cell has a concavity formed therein. The concavity has two edges, wherein increased pressure within the air cell causes contraction of the concavity moving the two edges closer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional patentapplication 60/444,545 filed Feb. 3, 2003, the entire contents of whichare incorporated herein by reference, and claims the benefit of U.S.provisional patent application 60/468,728 filed May 7, 2003, the entirecontents of which are incorporated herein by reference

BACKGROUND

The invention relates to inflatable manometers. Manometers are oftenused in medical procedures to monitor pressures in apparatus such asinflatable cuffs or manual resuscitators for a patient. For example, itis desirable to maintain the internal pressure of a tracheal tube cuffbelow 30 cmH₂O. Existing manometers are typically costly and can be avehicle for disease transmission, rendering widespread use of suchmanometers prohibitive. Accordingly, there is a need in the art for alow cost, accurate manometer for medical applications (e.g.,single-patient use disposable) and other applications.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the invention include an inflatable manometer having anair cell. The air cell has a concavity formed therein. The concavity hastwo edges, or other geometric features, wherein increased pressurewithin the air cell causes contraction of the concavity moving the twoedges closer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B depict inflatable manometers in embodiments of theinvention.

FIG. 2 depicts the manometer of FIG. 1A as pressure increases.

FIG. 3 depicts an inflatable manometer in an alternate embodiment of theinvention.

FIG. 4 depicts the manometer of FIG. 3 as pressure increases.

FIG. 5 depicts an inflatable manometer in an alternate embodiment of theinvention.

FIG. 6 depicts the manometer of FIG. 5 as pressure increases.

FIGS. 7A and 7B depict inflatable manometers in alternate embodiments ofthe invention.

FIG. 8 depicts an inflatable manometer in an alternate embodiment of theinvention.

FIG. 9 depicts the manometer of FIG. 8 as pressure increases.

FIG. 10 depicts an inflatable manometer in an alternate embodiment ofthe invention.

DETAILED DESCRIPTION

FIG. 1A depicts an inflatable manometer 10 in an embodiment of theinvention. Manometer 10 includes an air cell 12 coupled to a fluid inlet14. The manometer serves as an air cell pressure transducer thatindicates pressure of the fluid which may be gas, liquid, etc. The aircell 12 is formed by two sheets of material sealed along seal 16. In oneembodiment, the sheets of material are thermoplastic material and aresealed using known techniques such as heat sealing, ultrasonic welding,etc. The sheets of material are not limited to thermoplastic materialsand may be implemented using any flexible material such as rubber, gluedpaper, etc. The air cell 12 is generally circular and includes aconcavity 18 in the shape of a triangular wedge. It is understood thatthe air cell 12 and concavity 18 may have shapes other than thosedepicted in FIG. 1A. FIG. 1B depicts an alternate manometer similar tothat shown in FIG. 1A, but having differently shaped concavity 18.

A scale 20 is also formed from the same sheets defining the air cell 12and includes indicia 22 representative of pressure. The scale 20 andindicia 22 may be formed by molding the indicia 22 into thermoplasticsheets (e.g., heat stamping) or printing the indicia 22. The scale 20 ispositioned proximate to edge 24 of concavity 18. The scale 20 can bedesigned for different real units of measure, e.g., PSI. In alternateembodiments, scale 20 is affixed to air cell 12 and moves relative to astationary indicator.

FIG. 2 depicts manometer 10 of FIG. 1A as pressure in air cell 12increases. As the air cell 12 is inflated, the two edges that define theconcavity 18 will contract towards each other in response to increasinginternal fluid pressure. The pressure within the air cell 12 isrepresented by the position of edge 24 relative to scale 20. Thus, thesize and shape of the air cell 12, concavity 18 and scale 20 aredesigned to provide an accurate indication of pressure.

Inlet 14 may be coupled to a tube in fluid communication with a chamberfor which pressure monitoring is desired. Alternatively, manometer 10may be secured on a sidewall of a chamber with inlet 14 in fluidcommunication with the chamber. The seal 16 around inlet 14 may besecured to the chamber wall (e.g., heat sealed to thermoplastic chamber)to provide an integrated manometer.

FIG. 3 depicts an alternate manometer 30. Manometer 30 includes an aircell 32 and a fluid inlet 34. The manometer 30 indicates pressure of thefluid which may be gas, liquid, etc. The air cell 32 is formed by twosheets of material sealed along edges 36. Interior seals 38 define anumber of rectangular sub-cells 40, each having a concavity 42 at eachend defined by seals 36. In one embodiment, the sheets of materialdefining air cell 32 are thermoplastic material and are sealed usingknown techniques such as heat sealing, ultrasonic welding, etc. Thesheets of material are not limited to thermoplastic materials and may beimplemented using any flexible material such as rubber, glued paper,etc.

Air cell 32 and inlet 34 are positioned within a housing 50 having afirst and second sheet sealed along the periphery encasing the air cell32 and inlet 34. The first and second housing sheets may bethermoplastic material and are sealed using known techniques such asheat sealing, ultrasonic welding, etc. A scale 52 is also formed on thehousing 50 and includes indicia 54 representative of pressure. The scale52 and indicia 54 may be formed by molding the indicia 54 intothermoplastic sheets (e.g., heat stamping) or printing the indicia 54.The scale 52 is positioned proximate to a distal end 56 of air cell 32.The scale 52 can be designed for different real units of measure, e.g.,PSI.

FIG. 4 depicts manometer 30 as pressure in air cell 32 increases. As theair cell 32 is inflated, rectangular sub-cells 40 expand intocylindrically shaped cells, thereby reducing the length of the air cell32 in a linear direction. The pressure within the air cell 32 isrepresented by the position of distal end 56 relative to scale 52. Thedistal end 56 of the air cell 32 may be colored to more easily determinethe position of the end of the air cell 32 relative to the scale 52.Thus, the size and shape of the air cell 32 and scale 52 are designed toprovide an accurate indication of pressure.

Inlet 34 may be coupled to a tube in fluid communication with a chamberfor which pressure monitoring is desired. Alternatively, manometer 30may be secured on a sidewall of a chamber with inlet 34 in fluidcommunication with the chamber. The seal around inlet 34 may be securedto the chamber wall (e.g., heated sealed to thermoplastic chamber) toprovide an integrated manometer.

FIG. 5 depicts another manometer 60 in an alternate embodiment.Manometer 60 includes an air cell 62 and a fluid inlet 64. The manometer60 indicates pressure of the fluid which may be gas, liquid, etc. Theair cell 62 is formed by two sheets of material sealed along edges 66.The shape of seal 66 defines a number of sub-cells 68, each having aconcavity 70. The sub-cells are in fluid communication with each other,and inlet 64. The concavity 70 in FIG. 5 is a triangular wedge, but itis understood that other geometries may be used. In one embodiment, thesheets of material defining air cell 62 are thermoplastic material andare sealed using known techniques such as heat sealing, ultrasonicwelding, etc. The sheets of material are not limited to thermoplasticmaterials and may be implemented using any flexible material such asrubber, glued paper, etc.

Air cell 62 and inlet 64 may be positioned within a housing 72 having afirst and second sheet sealed along the periphery encasing the air cell62 and inlet 64. The first and second housing sheets may bethermoplastic material and are sealed using known techniques such asheat sealing, ultrasonic welding, etc. A scale 74 is also formed on thehousing 72 and includes indicia 76 representative of pressure. The scale74 and indicia 76 may be formed by molding the indicia 76 intothermoplastic sheets (e.g., heat stamping) or printing the indicia 76.The scale 74 is positioned proximate to a distal end 78 of air cell 62.The scale 74 can be designed for different real units of measure, e.g.,PSI.

FIG. 6 depicts manometer 60 as pressure in air cell 62 increases. As theair cell 62 is inflated, sub-cells 68 contract at concavity 70, asdescribed above with reference to FIG. 2, thereby reducing the length ofthe air cell 62 in a linear direction. The pressure within the air cell62 is represented by the position of distal end 78 relative to scale 74.The distal end 78 of the air cell 62 may be colored to more easilydetermine the position of the end of the air cell 62 relative to thescale 74. Thus, the size and shape of the air cell 62 and scale 74 aredesigned to provide an accurate indication of pressure.

FIG. 7A depicts a manometer 80 in an alternate embodiment of theinvention. Manometer 80 is similar to manometer 10 in FIG. 1A andsimilar components are labeled with the same reference numerals.Manometer 80 includes an indicator 82 extending from edge 24 ofconcavity 18. Rather than scale 20 formed in the sheet defining the aircell 12, manometer 80 includes a scale 84 printed on a separate card 86.The manometer 80 and the printed scale 84 may be encased within atransparent housing 88. The housing 88 includes an opening to access thefluid inlet 14 to the manometer 80. FIG. 7B depicts an alternatemanometer similar to that shown in FIG. 7A, but having differentlyshaped concavity 18.

FIG. 8 depicts a manometer 90 in an alternate embodiment of theinvention. The manometer 90 is formed from two sheets sealed together(e.g., thermoplastic sheets sealed together) to define an air cell 91and an inlet 96 for fluid. The sheets of material are not limited tothermoplastic materials and may be implemented using any flexiblematerial such as rubber, glued paper, etc. Inlet 96 is in fluidcommunication with a chamber for which pressure monitoring is desired.Manometer 90 includes two concavities 92 and 94, having differingcharacteristics. The concavities 92 and 94 have different widths so thateach notch will close at different pressures. It is understood thatother characteristics of concavities 92 and 94 may be varied includinglength, width and shape. The manometer 90 may also include a singleconcavity rather than two concavities. The single concavity maycorrespond to a minimum pressure that should be maintained or a maximumpressure that should be avoided. The distal end 98 of the manometer 90may serve as a fluid outlet so that manometer 90 may be positionedinline in a pressure system to indicate pressure of a chamber connectedto outlet 98.

FIG. 9 shows manometer 90 as pressure increases in air cell 91. As shownin FIG. 9, the opening of concavity 92 with the smaller width closes ata first predetermined pressure while concavity 94 has started tocontract. Concavity 94 with the larger width has started to contract andcloses at a second pressure. This allows an operator to determine thatair cell 91 has been inflated to a pressure between two limits withoutrequiring a scale indicating a numerical pressure value. Manometer 90may be used in a variety of applications including indicating pressureof pilot balloons associated with tracheal devices.

The inlet in the manometers of FIGS. 1–9 may be eliminated and the aircell pressurized with a fluid and sealed. In this embodiment, themanometer indicates ambient pressure in response to a difference betweenambient pressure and pressure in the air cell.

FIG. 10 depicts an inflatable manometer in an alternate embodiment ofthe invention. The manometer 10 is similar to that shown in FIG. 1 andincludes an outlet 15 in air cell 12. In this embodiment, the manometer10 serves as a flowmeter to indicate a pressure differential betweeninlet 14 and outlet 15. In this configuration, the manometer may be usedto indicate positive pressure, negative pressure or fluid flow. As longas the pressure within the manometer chamber 12 is positive to inflatethe chamber 12 and cause edge 24 to move relative to scale 20.

While the invention has been described with reference to exemplaryembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the essential scope thereof.Therefore, it is intended that the invention not be limited to theparticular embodiments disclosed for carrying out the invention, butthat the invention will include all embodiments falling within the scopeof the appended claims.

1. An inflatable manometer comprising: an air cell having a concavityformed therein, said concavity having two edges, wherein increasedpressure within said air cell causes contraction of said concavitymoving said two edges towards each other a scale positioned proximate tosaid air cell, a position of said air cell relative to said scale beingindicative of pressure within the air cell.
 2. The inflatable manometerof claim 1 wherein: one edge of said edges moves relative to said scalein response to pressure in said air cell, the position of said edgerelative to said scale being indicate of pressure.
 3. The inflatablemanometer of claim 1 wherein: said scale and said air cell areintegrally formed in thermoplastic material.
 4. The inflatable manometerof claim 1 wherein: said air cell is a circular air cell and saidconcavity is a section removed from said circular air cell.
 5. Theinflatable manometer of claim 1 wherein: said air cell includes aplurality of sub-cells in fluid communication, each sub-cell including aconcavity, wherein increased pressure within said air cell causescontraction of said air cell in a linear or radial direction.
 6. Theinflatable manometer of claim 5 further comprising: a housing containingsaid air cell, said scale being positioned on said housing.
 7. Theinflatable manometer of claim 5 wherein: a distal end of said air cellis colored.
 8. The inflatable manometer of claim 5 wherein: eachsub-cell is rectangular.
 9. The inflatable manometer of claim 5 wherein:each sub-cell is semi-circular.
 10. The inflatable manometer of claim 1wherein: said scale is printed on a card.
 11. The inflatable manometerof claim 10 further comprising: an indicator coupled to said manometer,said indicator moving relative to said scale in response to changes inpressure in said air cell.
 12. The inflatable manometer of claim 1further comprising: a second concavity formed in said air cell, saidconcavity having a first characteristic such that said concavity closesat a first pressure, said second concavity having a secondcharacteristic such that said second concavity closes at a secondpressure, said second pressure being greater than said first pressure.13. The inflatable manometer of claim 12 wherein: said firstcharacteristic is width and said second characteristic is width.
 14. Theinflatable manometer of claim 1 further comprising: a fluid inlet and afluid outlet coupled to said air cell, said manometer indicating apressure differential between said fluid inlet and said fluid outlet.15. The inflatable manometer of claim 14 wherein: said fluid inlet andsaid air cell are formed from thermoplastic sheets sealed to define saidfluid inlet and said air cell.